Switch actuating mechanism



Feb. 20, 1945. R, w GOFF 2,369,964

SWITCH ACTUATING MECHANISM Filed Jan. 11, 1944 2 Sheets-Sheet 1 Fig.1.Fig.2.

n kumwim Inventor: Robert W. Goff,

H His Attorney.

R. W. GOFF Feb. 20, 1945.

SWITCH ACTUATING MECHANI SM 2 Sheets-Sheet 2 Filed Jan. 11, 1944Inventor: Robert W. Goff,

His Attorneg.

Patented Feb. 20, 1945 SWITCH ACTUATING MECHANISM Robert W. Golf,Schenectady, N. Y., assignor to General Electric Company, a corporationof New York Application January 11, 1944, Serial No. 517,813

8 Claims.

My invention relates to electric switch actuating mechanisms, andespecially to limit switch actuating means providing for overtravel inboth directions of movement of an engageable operating lever.

The invention has particular application to and has been illustrated byway of example as applied to a double-throw limit switch of thesnap-action type having a switch actuating rocker lever alternativelylatched in one of two predetermined spaced circuit controlling positionsand slidable overcenter spring means for disengaging the latches andmoving the rocker lever.

It is a general object of my invention to provide a new and improvedlimit switch of the above character which shall be simple inconstruction, inexpensive and economical to manufacture, reliable inoperation, and characterized by a greatly improved operating life.

It is a more specific object of my invention to provide a new andimproved switch mechanism including means for converting rotation of anengageable operating lever about one axis to rotation of a switchactuating member about a perpendicular axis while permitting overtravelof the operating lever in both directions with respect to the actuatingmember.

My invention itself, together with further objects and advantagesthereof, may be fully appreciated by referring now to the followingdetailed specification taken in conjunction with the accompanyingdrawings, in which Fig. 1 is a front elevational view of a limit switchembodying my invention in one form; Fig. 2 is a cross-sectional viewtaken along the line 2-2. of Fig. 1 looking in the direction of thearrows; Fig. 3 is a rear elevational view of the limit switch of Figs. 1and 2; Fig. 4 is an exploded perspective View of the principal operatingparts of the switch shown at Figs. 1-3; and Fig. 5 is afragmentaryexploded perspective view of a part of the mechanism illustrated at Fig.4.

Referring now to the drawings, and particularly outlet vent l6 and atapped conduit'connection ll for the entrance of suitable electricconducting wires. 8

The double-pole double-throw limit switch illustrated in the drawingscomprises two spaced pairs of stationary contacts l8 and. I9 and amovable bridging contact member 20. The bridging contact 20 is slidablymounted upon a rectangular contact supporting bar 2| and i resilientlyheld in acentral position within a slidable yoke 22 by a pair of helicalcompression springs 23 positioned between the contact member 20 and theparallel sides of the yoke. As clearly shown at Fig. 4:, the yoke 22 isslidably mounted upon the contact supporting bar 2!. For the'purpose ofsliding the yoke 22longitudinally of the bar 2! to move the bridgingcontact 28, I have pro'v'ided'a pin 24 extending rearwardly from thebight of the yoke 22 into a slot 25 of a pivotally mounted switch arm2-6. The arm 25 forms part of a switch member comprising a rocker shaft21 fixedly connected at one end to the arm 26 and at the other end tothe center of a rocker lever 28. The rocker shaft 21 is rotatablyjournaled intermediate its ends in the casing partition or dividing wallII. The rocker lever 28 forms apart of the switch actuating mechanismand lies in the compartment I5.

The switch actuating mechanism will be best understood by referring nowparticularly to Figs. 3 and 4. From Fig. 3, it will be observed that apair of latch levers 29 and 30 are pivotally mounted upon pivot pins 3|and 32, respectively, in the base I0 and are biased into engagement withopposite ends of the rocker lever 28 by means of associated helicalcompression springs 33 and 3 4. respectively. The springs 33 and 34 areseated in casing abutments 35 and 36, respectively, which serve to limitthe latch disengaging movement of the associated latch members. i

Each latch member 29 and 30 is provided with a latching shoulder 31 withwhich the opposite ends of the .rocker lever 28 are alternativelyengageable. Each latch lever 29 and 30 is also provided with a limitstop shoulder'38 with which the opposite ends of the rocker lever 28 arealso alternatively engageable in inverse relation with respect to thelatch shoulders 31. That is, when the latch shoulder 31 of the lever 30is in engagement with one end of the rocker lever 28 as shown, the stopshoulder 38 of the other lever 29 is in engagement with the opposite'endof the rocker lever 28. Conversely, the latch shoulder 31 of the lever29 and the stop shoulder 38 of the lever 30 will besimultaneously'effective when the rocker lever 28 is in its othercircuit controlling position. The operation of the rocker lever 28 andthe function of the latch and stop shoulders 31 and 38 will be moreclearly understood after the remainder of the operating mechanism hasbeen more fully described.

The rocker lever 28 is actuated with a snapaction between two angularlydisplaced limiting circuit controllin positions by means of anovercenter mechanism comprising a spring pressed ball or roller. 39mounted in the movable end of a pivoted actuating lever 40 for slidingmovement longitudinally of the rocker lever .28 and overcenter withrespect to the rocker shaft'21. The ball 39 is biased outwardly from theend of the lever 40 by a helical compression spring 4| positioned withina counterbore in the lever 40. The actuating lever 40 itself is shown ashaving a rectangular cross-section, and is pivotally mounted upon afixed pivot pin 42 in the casing Hi.

Attached to the actuating lever 40 is a clutch arm comprising an'oifsetportion 43. extending from the pivot pin 42 substantially longitudinallyof an operating shaft 41. The operating shaft 41 is disposedsubstantially perpendicular to the pivot pin 42 and has fixed thereto alongitudinally grooved substantially cylindrical hub 46. Releasableclutching engagement between the operating shaft 41 andthe actuatinglever 40 is effected by a clutch pin 44 attached to the offset portion43 of theclutch arm and extending substantially perpendicular to theoperating shaft 41 into engagement with the grooved surface of the hub46. The clutch pin 44 is hollow, or may be counterbored at its end, toreceive a springnressed ball 45 which, together with the grooved hub 48,constitutes a releasable overriding ball and socket clutching connectionbetween the operating shaft 41 and the actuating lever 40.'

The hub 48 is shown in greater detail at Fig. 5, and comprises acylindrical body portion grooved longitudinally at 48 along one side andenlarged at one end to provide a pair of oppositely disposed stopshoulders 49 and 50. At a portion of reduced cross-section axiallydisplaced from the stop shoulders 49 and 50 and the grooved cylindricalportion, the hub 46 is provided with a radially extending arm A c-shapedleaf spring 52 is positioned circumferentially of the hub 46 and tograsp the arm 5| firmly between the open ends of the spring. While it isof course not necessary that the hub 46 be of reduced cross-section inthe region of the arm 5|, such reduction of cross' section is desirableso that the diametrical dimension of the C-shaped spring 52 may beapproximately the same as the diameter of the grooved cylindricalportion of the hub 46.

Referring now again to Figs. 2 and 4, it will be observed that theoperating shaft 41 is positioned parallel to the internal dividing wallII and sufficiently closely thereto that the stop shoulders 49 and 50 onthe hub 46 will engage the dividing wall to limit the rotation of theoperating shaft 41 in both directions. Mounted upon the dividing wall III also provide a fixed stop member 53 having a pair of spaced-apart dogs54 of substantially the same width as the radial arm 5| on the hub 46.The dogs 54 are arranged on opposite sides of the arm 5| and between theopen ends of the c-shaped spring 52. Thus, when no operatin torque isapplied to the shaft 41, the C-shaped spring 52 tends to close uponopposite sides of the fixed dogs 54 and to hold the radial arm 5| of thehub in a normal position between the dogs 54. The fixed stop member 53carrying the dogs 54 is slotted at 55 to provide for adjustable mountingupon the casing III by means of a bolt 55'. It will therefore be evidentthat the normal position of the operating shaft 41 may be changed withinlimits by adjusting the position of the fixed stop 53 upon the casingHi.

It may now be observed from Figs. 1 and 3, that the operating shaft 41extends through a wall of the casing ID to the outside thereof andcarries at its outer end an operating arm 56 upon the end of which maybe mounted an engaging roller 51. As illustrated in the drawings, theoperating arm or lever 56 is preferably mounted upon the operating shaft41 by means of a pair of serrated hubs, one upon the shaft 41 and oneupon the arm 56, arranged to be locked in engagement in any one of aplurality of positions by means of a bolt 59.

From the foregoing detailed description of the various parts of myswitch mechanism and the manner of their organization into a unitarywhole, it is believed that the operation of the device will be evidentfrom the following brief description. Assuming that initially themechanism is in the position shown in the drawings,

and referring particularly to Figs. 2, 3 and 4, movement of the bridgingcontact 20 from the position shown and into engagement with the contactsi9 is effected by movement of the operating arm 56 and shaft 41 in acounterclockwise dir'ection, as viewed at Fig. 4. Counter-clockwiserotation of the shaft 41 and the attached hub 44 moves the pin 44 on thelever 42 downwardly, as viewed at Fig. 4, by reason of the engagement ofthe ball 45 with the socket or groove 46. Downward movement of the pin44 effects counterclockwise rotation of the actuating lever 40 about itspivot pin 42. Such counterclockwise rotation of the shaft 41 andattached hub 46 also causes the radial arm 5| on the hub to spread theC-shaped spring 52 by moving the lower end of the spring, as viewed atFig. 4, away from the fixed clogs'54, while leaving the upper end of thespring in engagement with the upper sides of the dogs. Thecounterclockwise rotation of the actuating lever 40 thus effectedcontinues until the free end of the lever 40 strikes the latch lever 30.During this movement, the ball 39 is moved inwardly against the force ofthe spring 4| and overcenter with respect to the rocker shaft 21.However, the rocker lever 28 is not moved immediately because of itslatching engagement with the shoulder 21 of the latch lever 36. As soonas the actuating lever 40 strikes the lever 30 and moves it to its latchdisengaging position against the abutment 36 the rocker lever 28 isunlatched and the spring 4| becomes eifective to rotate the rocker shaft21 in a clockwise direction, as viewed at Fig. 4, until the right sideof the rocker lever 28 engages the limit stop shoulder 38 of the lever30. In this position it will be clear, by analogy with Fig. 3. that thelatch shoulder 31 of the latch lever 29 has moved under the left-handend of the rocker lever 28 to lock the rocker lever in the new position.It will be understood that rotation of the rocker shaft 21 and theattached switch arm 26 produces a sliding movement of the yoke 22 andbridging contact 20 along the contact supporting bar 2|.

As mentioned hereinbefore, rotation of the operating shaft 41 in bothdirections from its normal position is limited by engagement of the stopshoulders 49 and 50 with the dividing wall ll of the casing I0. However,the stop shoulders 49 and 50 are so positioned upon the hub 46 thatswitch actuating movement of the rocker shaft 28 in both directions maybe efiected before the stop shoulders 49 and 50 engage the casing; Theseshoulders serve, however, to limit overtravel of the operating lever 56with respect to the actuating lever 40. For example, in the event that,after the contact actuating movement described, a furthercounterclockwise rotation of, the operating arm 56 is effected. thespring pressed ball 45 will be forced out of the groove or socket 48 byreason of the fact that the actuating lever 40 is now in engagement withthe latch lever 30 and the latch lever 30 is in engagement with thefixed abutment 36. Thus, while no further counterclockwise rotation ofthe actuatin lever 40 is possible, a certain degree of overtravel of theoperating shaft 41 is permitted by forcing the ball 45 out of the groove48. This overtravel is limited only by engagement of the stop shoulder49 with the casing ll).

If now the operating arm 55 is released, the C shaped spring 52 willassume its normal shape and bring the radial arm 51 on the hub 46 backinto alignment with the protruding dogs 54 on the fixed stop 53. Theoperating shaft 41 and hub 46 will thus be moved in a clockwisedirection, as viewed at Fig. 4, and the actuating lever 49 rotated in aclockwise direction about its pivot pin 42. Upon such clockwise rotationof the actuating lever 40, it strikes the latch lever 29 and effectssnapaction of the rocker lever 28 in a manner entirely analagous to thatdescribed heretofore in connection with the latch lever 30. Such snapaction of the rocker lever 28 takes place before the stop shoulder 50 onthe hub 46 engages thecasing !0. If. now, the operating lever 56 isforced further in a clockwise direction, the ball 45 will again beforced out of the groove 48 and overtravel of the shaft 47 permitteduntil the stop shoulder engages the casing l0.

As noted hereinbefore, the normal positions of the operating shaft 41and actuating lever in may be changed by adjustment of the fixed stopmember 53. This adjustment will be more fully understood by referringagain to Fig. 4. As shown at this figure, the bridging contact is inengagement with the fixed contacts [8 when the switch mechanism is inits normal position. If now it is desired to maintain the contacts ii?nor mally open and the contacts l9 normally closed,

it is only necessary to loosen the bolt 56 of Fig. 2 and slide the fixedstop member 53 downwardly, as viewed at Figs. 2 and 4. In this mannerthe normal position of the operating shaft 47 and hub 46 may bedisplaced in a counterclockwise direction from the positions shown, sothat the actuating lever 40 is normally on the opposite side of therocker lever 28 and in engagement with the latch lever 30.

From the foregoing detailed description of the structure and operationof my electric switch, the purpose and advantages of the limiting stop38 on the latch levers 29 and Will become evident, Briefly, theseshoulders definitely determine the circuit controlling positions of therocker arm 28 without reliance upon the switch contacts themselves aslimiting stops. B this arrangement, backlash in the mechanism isprevented and its operating life is considerably extended. This featureof the limit switch disclosed herein by way of illustration of apreferred embodiment of my present invention is fully described andclaimed in my copending application Serial No. 471,137, referred tohereinbefore.

While I have described only a preferred embodiment of my invention byway of illustration,

many modifications will occur to those skilled in the art, and Itherefore wish to have it understood that I intend in the appendedclaims to cover all such modifications as fall within the true spiritand scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A motiontransmitting overtravel mechanism comprising a base, asubstantially cylindrical operating member mounted upon said base forrotation about a first axis, an actuating member pivotally mounted uponsaid base for rotation between two angularly spaced limiting positionsand about a second axis perpendicular to said first axis, and anoverriding clutch arm attached to said actuating member and offset .fromsaid second axis longitudinally of said first axis, said arm extendinginto releasable clutching engagement with said cylindrical operatingmember, thereby positively to connect said operating and actuatingmembers over a predetermined limited range of rotation of said operatingmember.

2. A motion transmitting overtravel mechanism comprising a base, asubstantially cylindrical operating member mounted upon said base forrotation about a first axis, means for biasing said operating member toa selectable normal position, an actuating member pivotally mounted uponsaid base for rotation between two angularly spaced limiting positionsand about a second axis perpendicular to said first axis, an overridingclutch arm attached to said actuating member at a point displaced fromsaid second axis longitudinally of said first axis and extending intoreleasable clutching engagement with said cylindrical operatin member,and means including said biasing means for selecting said normalposition normally to dispose said actuating member in either of saidlimiting Positions.

3. A motion transmitting overtravel mechanism comprising a base, asubstantially cylindrical operating member mounted upon said base forrotation about a first axis, an actuating member pivotally mounted uponsaid base for rotation between two angularly spaced limiting positionsand abouta second axis perpendicular to said first axis, said actuatingmember including an overriding clutch arm offset from said second axissubstantially longitudinally of said first axis and extendingsubstantially perpendicular to said first axis into releasable clutchinengagement with said operating member, and a pair of stop memberscarried by said operating member and dis-- posed to engage said base tolimit overtravel of said operating member in both directions and withrespect to said actuating member.

4. A motion transmitting overtravel mechanism comprising a base, asubstantially cylindrical operating member mounted upon said base forrotation about a first axis, means for biasing said operating member toa selectable normal position,

an actuating member pivotally mounted upon said tation of said operatingmember while permitting limited overtravel thereof in both directionwith respect to said actuating member, and means ineluding saidbiasingmeans for selecting said normal position normally to dispose saidactuating member in either one of said limiting positions.

5. A motion transmitting overtravel mechanism comprising a base, asubstantially cylindrical operating member rotatably mounted upon saidbase, a pair of stop members carried by said operating member andarranged to engage said base to limit rotation of said operating memberbetween two predetermined angularly displaced positions, an actuatingmember pivotally mounted upon said base for movement between twoangularly spaced limiting positions and about an axis substantiallyperpendicular to the axis of rotation of said operating member, and areleasable overriding clutch connection between the surface of saidcylindrical operating member and a portion of said actuating memberofiset from said pivotal axis longitudinally of said cylindricaloperating member, said clutch connection effecting movement of saidactuating member between said limiting positions within. the limits ofrotation of said operating member and permitting overtravel of saidoperating member in both directions.

6. A motion transmitting overtravel mechanism comprising a base, asubstantially cylindrical operating member rotatably mounted upon saidbase, a pair of stop members carried by said operating member andarranged to engage said base to limit rotation of said operating memberbetween two predetermined angularly displaced positions, an actuatingmember pivotally mounted upon said base for movement between twoangularly spaced limiting positions and about an axis substantiallyperpendicular to the aXis of rotation of said operating member, areleasable overriding clutch connection between the surface of saidcylindrical operating member and a portion of said actuating leveroffset from said pivotal axis longitudinally of said cylindricaloperating member,

said clutch connection effecting movement of said actuating memberbetween said limiting positions within the limits of rotation of saidoperating member and permitting overtravel of said operating member inboth directions, and ad- -justable means for biasing said operatingmemher to a selectable normal position within said limits of rotation,thereby normally to dispose said actuating member in either of saidlimiting positions.

7. A motion transmitting overtravel mechanism comprising a base, asubstantially cylindrical op-- erating member rotatably mounted uponsaid base, a pair of stop members carried by said operating member andarranged to engage said base to limit-*rotation of said operating memberbetween two predetermined angularly displaced positions, an actuatinlever pivotally mounted upon said base for rotation between twoangularly spaced limiting positions and about an axis substantiallyperpendicular to the axis of rotation of said operating member, a clutcharm attached to said actuating lever and extending from said pivotalaxis in a direction substantially longitudinal of said cylindricaloperating member, andv a spring-pressed ball and socket connectionbetween said clutch arm and the cylindrical surface of said operatingmember, said operating member effecting movement of said actuating leverbetween said limiting positions within the limits of rotation of saidoperating member and said ball and socket connection permittingovertravel of said operating member with respect to said actuating leverin both directions.

8. A motion transmitting overtravel mechanism comprising a base, asubstantially cylindrical operating member rotatably mounted upon saidbase and having a radially extending arm, a pair of stop members carriedby said operating member and arranged to engage said base to limitrotation of said operating member between two predetermined angularlydisplaced positions, an actuating lever pivotally mounted upon said basefor rota tion between two angularly spaced limiting positions and aboutan axis substantially perpendicular to the axis of rotation of saidoperating member, a clutch arm attached to said actuating lever andextending from said pivotal axis in a direction substantiallylongitudinal of said cylindrical operating member, a spring-pressed balland socket connection between said clutch arm and the cylindricalsurface of said operating member, said operating member ellectingmovement of said actuating lever between said limiting positions withinthe limits of rotation of said operating member and said ball and socketconnection permitting overtravel of said operating member with respectto said actuating lever in both directions, adjustable stop means forselectably determining the normal position of said operating member, anda G-shaped spring encircling said operating member and having its endspositioned normally to align said radially extending arm and saidadjustable stop.

ROBERT W. GOFF

